Process of reducing formaldehyde odor of aqueous mixtures containing methylolated carbamates

ABSTRACT

PROCESS FOR REDUCING FORMALDEHYDE ODOR OF AQUEOUS MIXTURES CONTAINING METHYLOLATED CARBAMATES COMPRISING THE STEPS OF MIXING SUCH AQUEOUS MIXTURES WITH 4,5-DIHYDROXY-2-IMIDAZOLIDONE AND/OR ITS METHYLOLATED AND/ OR ALKYLATED DERIVATIVES. THE PROCESS RESULTS IN AQUEOUS MIXTURE CONTAINING METHYLOLATED CARBAMATES AND METHYLOLATED 4,5-DIHYDROXY-2-IMIDAZOLIDINONE, AS SUCH OR IN ALKYLATED FORM, HAVING A FREE FORMALDEHYDE CONTENT OF NOT MORE THAN ABOUT 1.0 WEIGHT PERCENT.

United States Patent O 3,723,377 PROCESS OF REDUCKNG FORMALDEHYDE ODOROF AQUEOUS MIXTURES CONTAIN- IN G METHYLOLATED CARBAMATES MyrtleJoanuespangler, Danville, Va., assignor to Dan River Inc., Danville, Va.No Drawing. Filed Dec. 18, 1968, Ser. No. 784,935 Int. Cl. D06rn 15/58,15/54; C08g 32/28 US. Cl. 260-294 R 9 Claims ABSTRACT OF THE DISCLOSUREProcess for reducing formaldehyde odor of aqueous mixtures containingmethylolated carbamates comprising the steps of mixing such aqueousmixtures with 4,5-dihydroxy-2-imidazolidinone and/or its methylolatedand/ or alkylated derivatives. The process results in aqueous mixturescontaining methylolated carbamates and methylolated4,5-dihydroxy-2-imidazolidinone, as such or in alkylated form, having afree formaldehyde content of not more than about 1.0 weight percent.

BACKGROUND OF THE INVENTION (a) Field of the invention The presentinvention relates to novel processes for reducing formaldehyde odors ofaqueous mixtures containing methylolated carbamates to render suchmixtures more suitable in uses such as the treatment of textiles for thepurpose of imparting wrinkle resistance, crease and shape retention,stifiness and/ or other special effects.

(b) Description of the prior art In the preparation of aqueous mixturesof methylolated carbamates, the carbamate, e.g., an alkyl carbamate, isconventionally heated in an aqueous medium with formaldehyde to form thenitrogen-bonded methylol groups. The greater degree of methylolation,the greater the efiiciency of the methylolated carbamate in impartingthe desired properties to the subsequently treated fabric. In order toachieve as full a methylolation as possible a large molar excess offormaldehyde is usually employed. As a result, free formaldehyde inamounts of weight percent or higher remains in the aqueous mixture.

Methylolated carbamates could be highly valuable agents for thetreatment of textiles except for the uncomfortable, obnoxious, andunwholesome odors given off during its application to the textile.Fabrics treated with methylolated carbamates as compared toconventionally used textile resins of the same type are Whiter, i.e.,undergo less yellowing, and are less sensitive to weakening during acidwashes, such as those employed by commercial laundries. However, theodor problem has severely limited the use of methylolated carbamates onfabrics and prevented the full obtainment of the advantages of suchmaterials.

SUMMARY OF THE INVENTION The present invention provides methods forsubstantially eliminating the odor problem associated with aqueousmixtures containing methylolated carbamates and permits the utilizationof such mixtures to their fullest advantage. The methods of thisinvention provide for the reduction of formaldehyde odor of aqueousmixtures containing methylolated carbamates by heating such mixtures inthe presence of 4,5-dihydroxy-2-imidazolidinone or its methylolatedand/or alkylated derivatives.

The present invention also provides novel aqueous mixtures ofmethylolated carbamates and methylolated 4,5-dihydroxy-2-imidazolidinones, as such or in alkylated Patented Mar. 27,1973 form, containing not more than about 1.0 weight percent freeformaldehyde.

The invention is applicable to all types of methylolated carbamatesemployable in the treatment of fabrics. Such methylolated carbamatesinclude methylolated derivatives of: alkyl carbamates, such as, methyl,ethyl, propyl, isopropyl, butyl and isobutyl carbamates; hydroxyalkylcarbamates, such as, hydroxyethyl and hydroxypropyl carbamates;alkoxyalkyl carbamates, such as, ethoxyethyl, methoxyethyl,ethoxyisopropyl, butoxyhexyl, and stearoxyethyl carbamates;polyoxyalkylene carbamates, such as,

and alkoxypolyoxyalkylene carbamates, such as,

Alkyl-O(GxHzxO) CNH wherein Alkyl designates an alkyl group preferablyhaving 1 to 6 carbon atoms, x is an integer of 2 to 4 and n is aninteger of 2 or more, preferably 2 to 100.

Stated as a formula the methylolated carbamates employed includemethylolated derivatives of carbamates of the formula:

ROCNH2 wherein R is a monovalent hydrocarbon radical such as alkyl,preferably having 1 to 6 carbon atoms, cycloalkyl such as cyclohexyl,aryl Such as phenyl, aralkyl such as benzyl or alkaryl such as cresyl ortolyl; or a substituted monovalent hydrocarbon group substituted, forexample, with the hydroxy group, alkoxy groups, preferably having 1 to 6carbon atoms, aryloxy groups such as phenoxy,

cycloalkyloxy groups such as cyclohexyloxy, aralkoxy groups such asbenzyloxy, or alkaryloxy groups such as tolyloxy; or groups of theformula:

wherein R is a monovalent hydrocarbon group or a substituted monovalenthydrocarbon group as defined "above and x and n are integers as definedabove. The methylolated derivatives include those having one N- methylolgroup and those having two N-methylol groups per molecule as well asmixtures thereof.

These carbamates are well known in the art and are described in suchpatents as US. Pats. 3,402,989 and 3,391,181; British Pat. 309,108;French Pat. 1,030,430; and articles by Arceneaux et al. appearing onpages 37 through 41 of the American Dyestuif Reporter dated Oct. 30,1961, and on pages 45 through 46 of the American Dyestuff Report datedOct. 15, 1962.

Methylolation procedures, also, are well known and can be c-aried outwith aqueous formaldehyde in aqueous solutions or with paraformaldehydeunder anhydrous conditions. The methylolation is usually carried out tothe fullest extent possible so as to result in a more eflicient product.To accomplish this large molar excesses of formaldehyde are used.

4,5 dihydroxy-Z-imidazolidinone, hereinafter called DHEU, and itsmethylolated derivatives, e.g., 1,3-dimethylol-4,5-dihydroxy 2imidazolidinone, hereinafter called DMDHEU, are described in US. Pats.Nos. 2,731,472, 2,764,573 and 2,731,364. The precursors of thiscomposition are urea and glyoxal and these can be used as such in thisinvention. It is also possible to employ alkylated derivatives of thiscomposition such as are described in US. Pats. Nos. 2,764,573, 3,049,446and 3,029,164; German Pats. Nos. 1,171,437 and 1,171,438

and copending applications, Ser. Nos. 584,957 and 584,958 filed Oct.'7,1966, now both abandoned. It is also possible to use the procursors ofthe alkylated derivatives, namely a mixture of urea, glyoxal and analkanol or a mixture of 4,5-dihydroxy-2-imidazolidinone and an alkanol.When precursors are employed the stoichiometric amounts can be used orreasonable excesses of one of the precursors can be used or, where threeprecursors are used, excesses of one or two of the precursors can beemployed.

The amount of DHEU, or methylolated or alkylated DHEU, added dependslargely upon the amount of free formaldehyde present in the methylolatedcarbamate mixture. It has been found that one mol of DHEU and/oralkylated derivative, added or capable of being formed for each 2 molsof free formaldehyde, i.e., 0.5 mol of DHEU per mol of freeformaldehyde, reduces the free formaldehyde content down to 0.4 weightpercent or less and substantially eliminates the formaldehyde odor.Lesser amounts, for example, down to 0.5 mol per 2 mols of freeformaldehyde, reduce the free formaldehyde, i.e., 0.25 mol of DHEU permole of free formaldehyde, to a lesser extent and can be used toadvantage, especially in those treatments where small amounts offormaldehyde odor an be tolerated. More than 1 mol per 2 mols of freeformaldehyde can be used without deleterious effects. If desired, partlymethylolated DHE'U or its derivatives can be used or additionalformaldehyde can be added to methylolate any amounts of DHEU, or itsderivatives, present over and above the level of 1 mol per 2 mols offree formaldehyde.

There are at least two methods available for measuring free formaldehydein methylolated carbamate mixtures. The DeJong method is described inRec. Trav. Chim., 71, 643-890, 1952, and involves an iodometrictitration.

The direct titration method of measuring free formaldehyde involves themeasurement of the amount of sodium hydroxide released when sodiumsulfite is added to and reacts with free formaldehyde of themethylolated carbamate solution:

CH O+Na SO +H O NaOH+CH NaSO OH In this procedure, 15 grams of themethylolated carbamate solution are diluted to 150 grams with distilledwater to form a test sample. Fifty grams of the sample are mixed withice and pH is adjusted to 9.3 with aqueous sodium hydroxide. Fifty ml.of an aqueous sodium sulfite solution (120 g./liter) having a pH of 9.3is cooled and added to the chilled sample. The pH of the resultingsolution increases because of the liberation of sodium hydroxide byreaction of formaldehyde with sodium sulfite. The solution then istitrated back to pH 9.3 with 0.5 N HCl aqueous solution. The percentfree formaldehyde is calculated from the amount of HCl solution neededto adjust pH to 9.3.

The mechanism producing the reduction or substantial elimination offormaldehyde odor cannot be easily explained. A phenomenon has beenobserved in the unexpected substantial decrease in free formaldehydewhen free formaldehyde in aqueous mixtures of fully methylolated DHEU,i.e., DMDHEU, and added Formalin were determined by the direct titrationmethod. It was found that aqueous mixtures which should theoreticallycontain various amounts of free formaldehyde up to about 7.1 weightpercent because of the Formalin added, actually contained far less freeformaldehyde as actually determined by direct titration. The 7.1 weightpercent level, in the mixtures tested, corresponds to a mol ratio ofabout 2 mols formaldehyde added via the Formalin per mol of DMDHEU.Above the approximate 7.1 weight percent level the expected amounts offree formaldehyde were observed. At first, a complexing theory Waspropounded but was later discarded. After considerable effort, thephenomenon still has not been satisfactorily explained.

The temperature of forming the aqueous mixtures of methylolatedcarbamate and DHEU or its methylolated or methylated derivative is atleast F. and preferferably in the range of about 100 F. to about 140 F.and the initial pH is preferably adjusted to about 4.0 to about 9.5.

Another significant advantage in the process of the present invention isthe surprising reduction in volatility of the methylolated carbamatewhich is especially useful in the application and handling of the morevolatile methylolated carbamates, such as methylolated methylcarbamates.

The compositions produced by the process of this invention are aqueousmixtures containing about 25 to about 95 mol percent of a methylolatedcarbamate and about 5 to about 75 mol percent of methylolated 4,5-dihydroxy-2-imidazolidinone and not more than about 1.0 weight percentfree formaldehyde. Preferably, the resulting compositions contain 55 to95 mol percent methylolated carbamate and 5 to 45 mol percentmethylolated 4,5-dihydroxy-Z-imidazolidinone. These novel compositionsare characterized by no objectionable formaldehyde odor.

As used herein the terms methylolated carbamate and methylolated4,5-dihydroxy-2-imidazolidinone" cover N-monomethylolated andN,N-dimethylolated derivatives as well as mixtures thereof.

Application of the compositions produced according to processes of thisinvention to fabrics is accomplished by any of the many well knownmethods. Well known curing catalysts and other additives such assofteners can be incorporated into the compositions before applicationby the fabric. The compositions are very useful for imparting wrinkleresistance and/ or crease retention to cellulosic fabrics such as cottonand blends of cotton with synthetic fibers, especially polyester fibers.After application to the fabric, the composition can be fully cured,partly cured or substantially uncured. When fully cured, wrinkle andcrease resistance are imparted. When partly cured or substantiallyuncured, the fabric can be shaped and fabricated into an article such asa garment and then post-cured to impart wrinkle resistance to some areasand shape retention, such as durable creases and pleats, to other areas.

DESCRIPTION OF SPECIFIC EMBODIMENTS The following examples are presentedwherein, unless otherwise specified, parts and percentages are on aweight basis. Free formaldehyde contents were measured by the directtitration method.

EXAMPLE 1 An aqueous mixture containing 5000 parts of methyl carbamateand 9200 parts of a 37% aqueous solution of formaldehyde was preparedand the pH was adjusted to about 10.3 to 10.6 with 26 parts of 50%aqueous sodium hydroxide. The mixture was heated at about to F. forabout one hour to result in an aqueous mixture of methylolated methylcarbamate containing about 3.2 weight percent or about 15.2 mols offormaldehyde as measured by the direct titration method. The combinedformaldehyde was calculated to be about 98.3 mols and, based on suchcalculations, the solution contained about 31.6 mols of thedimethylolated derivative and about 35.1 mols of the monomethylolatedderivative.

At the end of the above mentioned period of one hour at 130 to 135 F.,7670 parts of a 43% solids aqueous solution of1,3-dimethylol-4,5-dihydroxy-2-imidazolidinone was added to the abovementioned aqueous mixture of methylolated methyl carbamate. Theresulting mixture was cooled to 100 F. and filtered.

The resulting composition was computed to have about 78.3 mol percent ofmethylolated methyl carbamate including 21.7 mol percent of methylolated4,5-dihydroxy- Z-imidazolidinone. It contained about 0.7% freeformaldehyde as determined by the direct titration method and about 52%solids by vacuum drying. When applied to a 50:50 cotton-polyester fabricno objectionable odor ensued. The composition was partially cured on thefabric and a permanent press garment was made from the partially curedfabric. In addition to reduced odor, the fabric treated with thecomposition showed less discoloration on curing, lower chlorineretention damage, better soil release properties and less yellowing onextended chlorine bleaching, than fabrics treated with each of the resincomponents alone.

EXAMPLE 2 An aqueous mixture was prepared from 150 grams methylcarbamate crystals (2 mols) and 410 grams of a 37% aqueous formaldehydesolution (5 mols of formaldehyde). The pH of the resulting mixture wasabout 4 at C. The pH was raised to about 9.8 by adding 0.6 gram of 50%aqueous sodium hydroxide. The temperature of the resulting aqueousmixture was raised to 60 C. over a period of one hour and held thistemperature for an additional hour. Then the mixture was cooled to 30 C.and was found to have a pH of about 9.3 and a free formaldehyde contentof about 8.58% (48 grams, 1.6 mols of formaldehyde) as determined bydirect titration. The combined formaldehyde was calculated to be about3.4 mols and, based on such calculations, the mixture contained about1.4 mols of dimethylol methyl carbamate and about 0.6 mol ofmonomethylol methyl carbamate.

About 180 grams (1.52 mos) of 4,5-dihydroxy-2- imidazolidinone crystalswere added to the mixture, and the mixture was heated to about 40 C. Itstemperature then increased to 57 C. exothermically and the mixture wasthen held at this temperature for one hour. Thereafter, it was cooled toapproximately room temperature and was found to have a pH of 6.1 and afree formaldehyde content of about 0.42% by the direct titration method.The final composition, based on calculations, contained about 1.4 molsN,N-dimethylol methyl carbamate, about 0.6 mol N-monomethylol methylcarbamate, about 1.5 mols 1,3-dimethylol-4,5-dihydroxy2- imidazolidinoneand about 0.104 mol free formaldehyde.

EXAMPLE 3 The same aqueous mixture of methyl carbamate and formaldehydewas prepared as described in Example 2, except that 0.7 gram of 50%aqueous sodium hydroxide was added to raise the pH to about 10. Theresulting mixture was heated for 35 minutes to 60 0., held at thistemperature for an additional hour and then cooled to 30 C. Theresulting mixture was found to have a pH of 9.9 and 10.56% (59.2 grams,1.98 mols) of free formaldehyde as determined by the direct titrationmethod. The combined formaldehyde was calculated to be about 3.02 molsand, based on such calculations, the mixture contained about 1.02 molsdimethylol methyl carbamate and about 0.98 mol of monomethylol methylcarbamate. About 180 grams (1.52 mols) of 4,5-dihydroxy-2-imidazolidinone crystals were added to the mixture and the mixture washeated to 51 C. over a period of 45 minutes. Thereafter, the mixture washeld at a temperature of 43 C. for an additional hour. The resultingmixture was cooled to about room temperature and was found to have a pHof 7.1 and a free formaldehyde content of about 0.12% as determined bythe direct titration method. The final composition, based oncalculations, contained about 1.02 mols N,N-dimethylol methyl carbamate,0.98 mol N-monomethylolmethyl carbamate, about 0.9 mol1,3-dimethylol-4,S-dihydroxy-Z-imidazolidinone and about 0.03 mol freeformaldehyde.

EXAMPLE 4 As an illustration of the previously mentioned phenomenon,several aqueous solutions were prepared con- TABLE I.WEIGHT PERCENT FREEFORMALDEHYDE Theory Found Solution number:

Another series of test were performed in a similar manner usingdifferent amounts of formaldehyde set forth in Table II below under theheading Theory and using about 33.5 weight percent of the methylatedN,N- dimethylol-4,5-dihydroxy-2-imidazolidinone prepared in accordancewith composition A of Example 2 of copending application Ser. No.584,957, filed Oct. 7, 1966, in place of the DMDHEU used in solutions 1to 13 above. The free formaldehyde content of each solution as actu allydetermined by the direct titration method was measured and the valuesobtained are listed in Table II below under the heading Found.

TABLE II.WEIGHT PERCENT FREE FORMALDEHYDE In each case where freeformaldehyde was added, far less free formaldehyde was found than theamount added, up to approximately 7%.

EXAMPLE 5 An aqueous mixture (about 762 wt. pts.) containing 3 moles ofmethyl carbamate and 6.75 moles of formaldehyde was prepared and pH wasadjusted to about 10.5. The mixture was reacted at about 55 C. for aboutfour minutes to result in an aqueous mixture of N,N-dimethylol methylcontaining 7 weight percent or about 1.8 mols of formaldehyde asmeasured by the direct titration method. The combined formaldehyde wascalculated to be about 4.95 mols and, based on such calculations, thesolution contained about 1.95 mols of the dimethylolated derivative andabout 1.05 mols of the monomethylolated derivative.

One mol of glyoxal (40 wt. percent aqueous solution) and one mol of ureawere then added and the pH was adjusted to 9.0. The mixture was held at50 C. for three hours and allowed to age overnight. At the end of thistime the pH had dropped to 6.3 and the amount of free formaldehyde haddropped to about 0.4 weight percent or about 0.13 mol.

The resulting composition was computed to have 75 mol percent ofmethylolated methyl carbamate including 1.95 mols of N,N-dimethylolmethyl carbamate, and 1.05 mols of N-methylol methyl carbamate, and 25mol percent of methylolated 4,5-dihydroxy-Z-imidazolidinone including0.67 mol of N,N' dimethylol-4,5-dihydroxy-2- imidazolidinone and 0.33mol of N-methylol-4,5-dihydroxy-2-imidazolidinone, When applied to a50:50 cotton-polyester fabric no objectionable odor ensued. Thecomposition was partially cured on the fabric and a permanent pressgarment was made from the partially cured fabric.

EXAMPLE 6 An aqueous solution was prepared containing 55 weight parts ofFormalin (37% aqueous formaldehyde), 22.5 weight parts methyl carbamateand 1.4 weight parts of 50% aqueous sodium hydroxide. The pH of theresulting solution reached about 104:0.1. The solution was maintained at55 C. for forty-five minutes to methylolate the carbamate after whichtime it contained 9.5 weight percent free formaldehyde.

Thereafter, 12.0 weight parts of a 40% aqueous glyoxal solution, 5.0weight parts of urea, and 1.2 weight parts of aqueous sodium carbamatewere added. The pH was adjusted to 9.3. The resulting solution wasmaintained at 55 C. for 2% hours and the pH dropped to a point in therange of 7.3 to 7.6 during this period. The free formaldehyde contentwas measured and found to be 0.5 to 0.6 weight percent.

Twenty-five weight parts of water were added to the solution to reducethe solids content down to 44 percent. The pH of the diluted solutionwas in the range of 7.0 ot 7.5 and it contained 0.4 to 0.5 weightpercent free formaldehyde.

The resulting solution was computed on the basis of full methylolationof the carbamate to have about 78.2 mol percent of methylolated methylcarbamate, about 21.8 mol percent of methylolated4,5-dihydroxy-2-imidazolidinone. When applied to a 50:50cotton-polyester fabric no objectionable odor ensued. The compositionwas partially cured on the fabric and a permanent press garment was madefrom the partially cured fabric.

What is claimed is:

1. Method of reducing odor due to free formaldehyde in an aqueousmixture containing methylolated carbamate obtained by reacting in anaqueous medium formaldehyde with a carbamate selected from the groupconsisting of a carbamate of the formula:

wherein R is a member selected from the group consisting of alkyl having1 to 6 carbon atoms, cyclohexyl, hydroxyalkyl having 1 to 6 carbon atomsand alkoxyalkyl wherein each of the alkoxy and allyl contains 1 to 6carbon atoms, and a carbamate of the formula:

wherein R is a member selected from the group consisting of hydrogen andalkyl having 1 to 6 carbon atoms, x is an integer of 2 to 4 and n is aninteger of 2 to 100, said method comprising mixing said aqueous mixturewith at least 0.5 mol of 1,3-dimethylol-4,S-dihydroxy-Z-imidazolidinoneand methylated derivatives thereof per 2 mols of free formaldehyde insaid aqueous mixture, and heating the resultant mixture at an initial pHof from 9.0 to 9.9 and a temperature of at least F.

2. Method as claimed in claim 1 wherein said imidazolidinone is presentin an amount up to 1 mol per 2 mols of free formaldehyde in said aqueousmixture.

3. Method as claimed in claim 1 wherein said resultant mixture is heatedat a temperature of about 100 F. to about F.

4. Method as claimed in claim 1 wherein methylolated carbamate ismethylolated alkyl carbamate.

5. Method as claimed in claim 4 wherein said methylolated carbamate ismethylolated methyl carbamate.

6. Method as claimed in claim 1 wherein said methylolated carbamate ismethylolated alkoxyalkyl carbamate.

7. Method as claimed in claim 6 wherein said methylolated carbamate ismethylolated ethoxyethyl carbamate.

8. Method as claimed in claim 1 wherein said imidazolidinone is 1,3dimethylol-4,5-dihydroxy-2-imidazolidinone.

9. Method as claimed in claim 1 wherein said imidazolidinone ismethylated 1,3 dimethylol-4,5-dihydroxy 2- imidazolidinone.

References Cited UNITED STATES PATENTS 3,052,570 9/1962 Polansky et a1260-84 21 3,219,632 11/1965 Frick et al. 260-72 b 3,369,858 2/1968Lourigan et al. 8-116.3 3,391,181 7/1968 Scheuerl 8-116.3 3,402,9899/1968 Canter et al. 8-116.3 3,416,880 12/1968 Kullman et al. 8-116.33,425,208 2/1969 Shippee et al 8116.3 3,454,423 7/1969 Cohen, et al.117-1394 3,497,471 2/1970 Cohen et al. 260-29.4 3,590,100 6/1971 Weiland8-116.3

OTHER REFERENCES Reid et al.: American Dyestuif Reporter, vol. 59, No.6, pp. 26-28, 32 and 34 (1970).

GEORGE F. LESMES, Primary Examiner J. CANNON, Assistant Examiner US. Cl.X.R.

2-243; 8-115.7, 116.3, DIG 14; 38-144; 117-139.4, 138.8 F, 161 LN;260-72 B, 849

